1. Technical Field
The present invention relates to a switch, particularly to a push-button switch.
2. Related Art
Conventionally, for example, International Patent Publication No. 8-504050 discloses a flat key switch as a switch in which a contact can be opened and closed by a pressing operation. FIG. 11 is an exploded perspective view illustrating a configuration of the flat key switch disclosed in International Patent Publication No. 8-504050.
As illustrated in FIG. 11, a key switch 100 of International Patent Publication No. 8-504050 is accommodated in a housing including a lower portion 110 and a lid portion 120 covering the lower portion 110. The key switch 100 is opened and closed by switching between contact and non-contact of a fixed contact piece 144 and a contact shoe 146. The contact shoe 146 is constructed by a cyclic thin-plate 150. When a push-rod 130 is pushed in, the cyclic thin-plate 150 is bent in a direction perpendicular to a direction, in which the push-rod 130 is pushed in, by an opening and closing cam 140 provided in the push-rod 130. The contact shoe 146 constructed by the cyclic thin-plate 150 moves relative to the fixed contact piece 144 to come into contact with or separate (becomes the non-contact) from the fixed contact piece 144. Thus, the key switch 100 of International Patent Publication No. 8-504050 is opened and closed by switching between the contact and the non-contact of the fixed contact piece 144 and the contact shoe 146 in the direction perpendicular to the direction in which the push-rod 130 is pushed in. Therefore, the key switch 100 is suitable for the switch in which an appearance has a flat structure.
However, in the key switch of International Patent Publication No. 8-504050, unfortunately it is necessary to enlarge dimensions of the appearance when a member is disposed in a center of the key switch.
In the key switch 100 of International Patent Publication No. 8-504050, the contact shoe 146 constructed by the cyclic thin-plate 150 is disposed on a side of one of side surfaces constituting a quadratic prism of the lower portion 110. The cyclic thin-plate 150 has a cyclic structure because the cyclic thin-plate 150 is bent in the direction perpendicular to the direction in which the push-rod 130 is pushed in. Because a certain degree of flexibility is provided to the cyclic structure, the dimensions of the cyclic thin-plate 150 are enlarged in the direction perpendicular to the direction in which the push-rod 130 is pushed in.
Thus, a space of the contact shoe 146 constructed by the cyclic thin-plate 150 is enlarged in the key switch of International Patent Publication No. 8-504050. Therefore, it is difficult that the member is disposed in the center of the key switch without changing the dimensions of the appearance. For example, in a lighted push-button switch, desirably an LED light source is disposed in a central position with respect to a button operating surface such that the button operating surface is homogeneously illuminated with light. In the case where the key switch of International Patent Publication No. 8-504050 is applied to the lighted push-button switch, it is difficult that the LED is disposed in the center of the operating surface of the key switch without changing the dimensions of the appearance. It is necessary to enlarge the dimensions of the appearance of the key switch in order to dispose the LED in the center of the operating surface of the key switch.